The present invention relates generally to data communication transmitters and, more specifically, to systems and methods to speed-up operation of a driver, such as a differential driver.
In a typical communication system, inter-chip high-speed communication is generally limited by the performance of driver and receiver circuits at the interface of communicating chips. Inherent driver circuit limitations often limit data rates that can be effectively implemented in accordance with any given design standard. High-speed chip-to-chip signaling often provides a bottleneck in the design of various types of systems, such as motherboards, optical transmission links, intelligent network hubs, routers and other systems.
Driver designs are challenged to meet the demands of ever increasing data rate requirements. Consequently, circuit designers continually search for ways to improve the rise times and fall times of drivers, such that driver switching speeds can be pushed higher and higher.
Standards have been established for high-speed signal handling applications including, for example, low voltage differential signaling (LVDS) and positive emitter-coupled logic (PECL). These standards enable the design of high-speed systems with minimum power dissipation and low electromagnetic interference (EMI). However, inter-chip high-speed communication is still limited by the performance of driver and receiver circuits at the interface of these circuits.
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is intended to neither identify key or critical elements of the invention nor delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
The present invention generally provides systems and methods to facilitate or speed up transitions associated with signals at one or more outputs of a driver. Transitions (e.g. high to low and/or low to high) associated with an output of the driver are employed to implement control, which can be applied as a pulse in response to a transition. The control operates to speed up the transition at the output of the driver, such as can reduce driver switching times of the driver and enable a corresponding increase in data transmission rates.
For example, the transitions can correspond to voltage transitions (e.g. high to low and/or low to high) associated with operation of the driver. The transitions can be detected at the output node (or nodes) or at other locations internal to the driver. The pulse can implement desired current control based on a transition, which is applied to speed up a transition at the output of the driver.
In a particular aspect of the present invention, one or more coupling devices, such as capacitors, can be employed to store a charge. For example, the capacitor(s) is operatively connected to an output of the driver to provide positive feedback (e.g., feedforward control) based on the occurrence of a transition at the output. The capacitor thus can couple a pulse during a transition that operates to improve switching speeds in the output stage of the driver.
Another aspect of the present invention provides a method to facilitate a transition at the output stage of a differential driver circuit. The method includes monitoring and detecting a transition of a signal associated with the output of the driver circuit. Based on the detection of the transition, the method further includes providing a short supplemental pulse to improve the switching speed at the output stage of the driver.
The following description and the annexed drawings set forth in detail certain illustrative aspects of the invention. These aspects are indicative, however, of but a few of the various ways in which the principles of the invention may be employed and the present invention is intended to include all such aspects and their equivalents. Other advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.